The workscope included the replacement of two 24" launcher valves on the oil export line from Dunlin to Cormorant Alpha.
The company used its in-house designed Remote Tecno Plug system which provides double block and bleed isolation.
STATS said this technology eliminates the need for communication tethers or specially modified pig trap doors and allowed the old valves to be removed without the requirement for tether management.
In preparation, STATS carried out a piggability study on the oil export line and trialled the Remote Tecno Plug onshore with a client witnessed factory acceptance test with a purpose built test fixture simulating the offshore pipeline configuration.
The shutdown was scheduled for up to 80 days and as the Tecno Plug was the primary isolation on the export pipeline it had to be capable of meeting this scheduled duration, the company said.
STATS Group head of intervention and isolations Dave Vernon said the Remote Tecno Plug was constantly monitored and remained stable and in location for 72 days while maintenance operations were completed.
